Clinker and white portland cement with a high sulfur content derived from a high sulfur content pet-coke used as fuel

ABSTRACT

The present invention relates to a family of white clinker compositions with a high capacity to fix sulfur derived from a high content pet-coke used as fuel in the manufacture thereof, which further exhibits low fuel consumption and fast setting, achieved by being comprised of the following amounts of clinker phases in percentage by weight: 3CaO.SiO 2  (C 3 S): 40 to 75, 2CaO.SiO 2  (C 2 S): 10 to 35, 3CaO.Al 2 O 3  (C 3 A): 0 to 15, CaO.SO 3  (CS): 0 to 10, 4CaO.3Al 2 O 3 .SO 3  (C 4 A 3 {haeck over (S)}): 2 to 15, 11CaO.7Al 2 O 3 .CaF 2  (C 11 A 7 .CaF 2 ): 0 to 5, total % CaF 2 : 0.3 to 1.5 measured as CaF 2 , % Fe 2 O 3 : 0 to 0.5 and a SO 3  content between 1.5 to 5% by weight obtained through the calcination of a raw meal containing CaO, SiO 2 , Al 2 O 3 , and CaF 2 , using as fuel, pet-coke with a sulfur content higher than 5% and at temperatures between 2192 and 2462° F., without the addiction of essentially any additive containing SO3 in the raw meal.

RELATED APPLICATION (FOREIGN PRIORITY CLAIM)

Benefit is claimed of the prior filing date of Mexican application no.PA/a/2002/012235, filed Dec. 10, 2002 in accordance with 37 CFR §1.55and 35 USC §119.

FIELD OF THE INVENTION

The present invention is related to a new family of clinker and whiteportland cement compositions, and more particularly, to a family ofwhite clinker compositions with a high content of sulfur derived mainlyfrom sulfur-containing fuel, and the properties of the cements thusobtained.

BACKGROUND OF THE INVENTION

Portland cement clinker is basically composed of four crystallinestages: alite (tricalcium silicate): 3CaO.SiO₂ (C₃S), belite (dicalciumsilicate): 2CaO.SiO₂ (C₂S), tricalcium aluminate: 3CaO.Al₂O₃ (C₃A) andtetracalcium aluminoferrite: 4CaO.Al₂O₃.Fe₂O₃ (C₄AF). The latter is theonly one colored; and, therefore, the only one responsible for thecharacteristic color of the ordinary gray Portland cement.

The ordinary Portland cement is the product from the ground Portlandcement clinker and a setting regulator, which traditionally has beengypsum (CaSO₄.2H₂O).

Processes and plants used for manufacturing white Portland Cement (P.C.)clinker are widely known in the art. Generally, the manufacturingprocess for White P.C. clinker differs from that for Gray P.C. clinkerin the following basic aspects:

(1) Chemical: To obtain a White P.C. clinker, the total Fe₂O₃ contentfrom the raw materials for the White P.C. clinker is controlled and mustbe less than 0.5% by wt. This implies eliminating the main melting agent(flux) from the gray P.C. clinker. Consequently, the liquid stage isessentially formed only from calcium aluminates, which will crystallizeafter a cooling process as C₃A. This thus eliminates formation of theC₄AF solid solution; which is responsible for the gray P.C. color.

(2) Sintering: Eliminating the main flux found in gray Portland cementclinker, results in white P.C. clinker; which with less fluxconsequently increases over all the temperature for the liquid stage;from 2440.4° F. (1338° C.) for a gray P.C. clinker to 2642-2678° F.(1450°-14700) for a white P.C. clinker. This thus requires a higher fuelconsumption during sintering as compared to the gray P.C. clinkersintering process.

(3) Cooling: In the manufacturing process of white P.C. clinker,typically the clinker cooling process is more difficult than for thecooling process in the gray P.C. clinker manufacturing process, whereone is trying to stabilize most of the iron on a reduced state(Fe^(2+)′ that is less chromophore than (Fe) ³⁺).

Despite the differences above-mentioned between both types of Portlandcement clinker manufacturing processes, basically the two Portlandcement clinkers are generally constituted by the same main mineralogicalstages: C₃S, C₂S, C₃A and, exclusively for Portland cement gray clinker,C₄AF.

Advantages of a white P.C. over a gray P.C., are basically their whitecolor, for which it is widely used for exposed structures and texturizedelements, which can be white or colored. It is also common that whitePortland cement develops better compression strength due to a highcontent of C₃A, as compared to a gray Portland cement. A disadvantage ofa white Portland cement is its low resistance to sulfates attack, mainlydue to the high content of C₃A, that reacts with environmental sulfatesand produces ettringite when mortar or concrete is hardened, causingfissures or cracking.

On the other hand, in the state of the art, it is known that sulfurcoming from traditionally used fuels for the cement industry, such asgas (non-sulfur containing), carbon (1-2% S), fuel oil (2-4% S) and lowsulfur content pet-coke (<5% S), is fixed on clinker in the form ofanhydrite, CaOSO₃ (C{haeck over (S)}), and in the presence of alkalileaching it forms alkaline sulfates: Na₂O.SO₃ and K₂O.SO₃. Saidanhydrite and alkaline sulfates fixing on the clinker is a desirablefactor since up to now it has represented the only way of extractingsulfur from the interior of the furnace, avoiding blockages andobstructions of the kiln itself, as well as the emission of SOx to theatmosphere.

In this way, sulfur, being semi-volatile, forms a cycle within thefurnace, which re-concentrates and once such sulfur reaches a criticalSO₃ evaporating concentration, that is associated with clustering in thekiln which makes kiln operation difficult and unstable, thereby reducingits production (and can even form blockages serious enough to result ina stoppage of the kiln itself).

On the other hand, fuel-oil cost is inversely proportional to its sulfurcontent. For this reason, high sulfur content pet-coke (S>5%) representsan opportunity for the cement industry due to its availability at alower cost.

Unfortunately, the use of such fuel is difficult, since it requiresspecial care for operation New methods have long been needed that couldease use without detriment to the furnace operation continuity.Currently, the use of the pet-coke as fuel, in one hand, generates thenecessary heat to maintain the process temperature; and on the otherhand, it produces a higher amount of SO₂, which can become large enoughto produce blockages in the pre-heater and form rings in the rotatingkiln. This causes operational troubles, reducing its efficiency and, inmore serious cases, actually interrupts operation.

On one hand, and particularly in relation to the Portland cementclinker, in the state of the art there are numerous efforts aimed tofacilities, equipment and/or processes design, for the use of solidfuels with a high sulfur content, in order to solve the problemsassociated with SO₂ formation and accumulation. However, most ofprocesses and/or plants that manufacture Portland cement clinker and usea solid fuel with a high sulfur content, present certain disadvantagessuch as complexity of processes and equipment, as well as highoperational costs. Examples of such efforts are disclosed in, forexample, the U.S. Pat. No. 4,465,460 entitled “Cement clinkerproduction” issued to Paul Cosar on Aug. 14, 1984; U.S. Pat. Nos.4,662,945 and 4,715,811 both entitled “Process and apparatus formanufacturing poor cement clinker in sulfur” issued to Thomas R. Lawallon May 5, 1987 and in Dec. 29, 1987 respectively; the U.S. Pat. No.6,142,771 entitled “Cement clinker production control using high sulfurcontent fuel within a rotating kiln with a Lelep-Lepol displaceable gridthrough the sulfur final analysis in the final product”, issued toJoseph Doumet on Nov. 7, 2000; Chinese Patent No. 1,180,674 issued toWang Xinchang et al on May 6, 1998 entitled “Method for producing highquality cement using pet-coke with a high sulfur content”.

A recent effort to solve problems associated to the use of high sulfurcontent coke, is disclosed by Mexican Application No. PA/a/2001/007229entitled “Method of producing cement clinker using high sulfur contentpet-coke” filed on Jul. 13, 2001 by Trademarks Europa, S.A. de C.V.,which is a subsidiary of the CEMEX group (see also the correspondingU.S. Pat. No. 6,599,123, issued Jul. 29, 2003). In this latterapplication is discussed a method to produce cement clinker that allowsa more economic and efficient use of fuels with a high sulfur contentsuch as pet-coke and that minimizes problems associated with blockagesand incrustations due to the high concentration of SO₂ and/or SO₃ in thesystem. In this document is described the production of a high qualitycement clinker that does not require addition of additives to improveits final physical properties.

On the other hand, there is another group of scientists andtechnologists who have focused their efforts on reducing Portland cementclinker sintering temperatures, through chemical modifications (of rawmix or raw meal), and have frequently used non-traditional mineralizersand fluxes. Examples of this group's efforts are generally described inthe U.S. Pat. No. 5,698,027 entitled “Method and Plant for manufacturingmineralized Portland cement clinker” granted to F.L. Smidth & Co., whichis related to a mineralizer such as gypsum, fluorite, etc., as a controlparameter for preventing or reducing problems associated with therotating kiln operation; the Spanish Patent No. 542,691 “Process forobtaining white clinker with a low fuel consumption using fluorite andsulphates as raw meal components”, describes a process for producing aclinker composition which is formed under lower temperatures as comparedto traditional temperatures for the Portland clinker manufacturing,forming a new liquid phase called fluorelestadite: 3C₂S.3CaO₄.CaF₂.However, said cements present some problems with strength development,over all, at early ages (1 and 3 days), even when strength increases atlong ages (28 days and more), as compared to strength developed bycommon Portland cement.

There is a third group of researchers who have found non-Portlandclinker cement compositions, based on the formation of a phase rich insulfur, calcium sulphoaluminate: 4CaO.3Al₂O₃.SO₃ (C₄A₃{haeck over (S)}).Said calcium sulphoaluminate based cements exhibit an accelerateddevelopment of initial strengths compared to Portland cement, due to the(C₄A₃{haeck over (S)}) hydration to form ettingite. Examples of thisbranch of development are U.S. Pat. No. 6,149,724 to Poo Ulibarri et al,granted to CEMEX in 2000, or the corresponding Canadian Patent No.2,193,339 and European Patent No. 0 812 811.

In 1994, U.S. Pat. No. 5,356,472 “Portland cement clinker and Portlandcement”, to Ivan Odler, disclosed a method for manufacturing grayclinkers under low forming temperatures, for example between 2102°F.-2462° F. (1150° C.-1350° C.). This clinker was formed by C₃S,(C₄A₃{haeck over (S)}) and preferably also C₄AF phases and practicallywithout C₂S and C₃A, if to the raw mix containing CaO, SiO₂, Al₂O₃, andFe₂O₃ was added an inorganic additive containing SO₃ and other inorganicadditive containing fluorine. Cement was obtained with strengthcomparable to that of conventional gray Portland cement, when the cementwas prepared with a clinker composition of 80% C₃S, 10% C₄A₃{haeck over(S)} and 10% C₄AF.

However, no prior art document is related to the main objective of thepresent invention; which is to produce a family of mineralogicalcompositions of white cement clinkers, formed by C₃S, C₂S, C₄A₃{haeckover (S)}, C₃A, C₁₁A₇.CaF₂, C{haeck over (S)} phases, without thepresence of C₄AF, with a high capacity to fix sulfur derived frompet-coke as a sulfur source, using the conventional infrastructure ofcement plants, for the production of white portland cements withcompression strength similar to or even greater than the strength ofconventional white Portland cement.

Therefore, it is an objective of the present invention to provide newclinker and white portland cement compositions with high capacity offixing sulfur coming from pet-coke with a high sulfur content, used asfuel.

Another objective of the present invention is to provide new clinker andwhite Portland cement compositions exhibiting low fuel consumption inits manufacturing process and having fast setting developing increasedcompression initial strengths.

It is further another object of the present invention to provide newclinker and white portland cement compositions using the conventionalcement Plants infrastructure.

BRIEF DESCRIPTION OF THE INVENTION

The present invention is related to a new family of white portlandcement clinker compositions, with a high capacity to fix sulfur derivedfrom pet-coke having a high sulfur content, used as a fuel in theproduction thereof, and to the white portland cement thus obtained withsuch properties. White portland cement clinker of the present inventioncomprises amounts of clinker phases in percentage by weight, as follows:from 40 to 75% of C₃S, from 10 to 35% of C₂S, from 0 to 15% of C₃A,without C₄AF, from 0 to 10% of C{haeck over (S)}, from 2 to 15% ofC₄A₃{haeck over (S)}, from 0 to 5 of C₁₁A₇.CaF₂, % CaF₂ total from 0.3to 1.5 measured as CaF₂, % Fe₂O₃ from 0 to 0.5%; and a content of SO₃between 1.5 and 5% by weight obtained through a raw meal calcinationmainly containing CaO, SiO₂, Al₂O₃, and CaF₂, using pet-coke as fuelwith a sulfur content higher than 5%, at temperatures ranging between2192 and 2462° F. (1200° C. and 1350° C.), without the addition of anyadditive containing SO₃ to the raw meal.

In the broader aspects of this invention, the SO₃ content in the clinkeris mainly provided by means of the organic fuel with a sulfur % greaterthan 5%. Specific additional sources of the SO₃ content in the clinkerare listed below (and in the claims).

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS OF THE INVENTION

The present invention is related to a new family of white portlandcement clinker compositions based on factors such as, for example, alite(C₃S) formation temperatures and calcium sulphoaluminate (C₄A₃{haeckover (S)}) decomposition; the use of high sulfur content organic fuelsthat provide cement clinker a SO₃ content of 1.5 to 5% by weight; andsintering temperature reduction. It is widely known that alite formationtemperature for a Portland cement clinker is approximately of 2516° F.(1380° C.), while calcium sulphoaluminate decomposition temperature fora white portland cement clinker is approximately 2462° F. (1350° C.).Taking into account these criteria among others, the inventors havediscovered that a new family of white portland cement clinkercompositions can be obtained through the use of adequate mineralogicalphases (C₃S, C₂S, C₃A, C{haeck over (S)}, C₄A₃{haeck over (S)} andC₁₁A₇.CaF₂) of cement clinker and through the reduction of sinteringtemperature, using a high sulfur content organic source, without havingproblems associated with the use of said organic source as fuel (forexample, high sulfur content pet-coke) which has a sulfur content higherthan 5%.

White portland cement, prepared from the above described clinker byfixing sulfur supplied mainly by high sulfur content pet-coke (>5% S),in the form of calcium sulphoaluminate, C₄A₃{haeck over (S)}, exhibitsan excellent increase in the compression strength. It particularlyexhibits an accelerated development of initial strengths, especiallyduring the interval of time from 1 to 3 days.

Specific reference is made to the following illustrative embodiments:

Total content of SO₃ in cement shall be between 3 and 10% (or preferablybetween 3.5 and 10%) by weight obtained through the calcination of rawmeal containing CaO, SiO₂, Al₂O₃ and CaF₂, using as fuel pet-coke with asulfur content higher than 5%, without the addition of any additivecontaining SO₃ in the raw meal.

A white Portland cement clinker can include the following amounts fromthe clinker phases in % by weight:

-   -   3CaO.SiO₂ (C₃S): 40 to 75,    -   2CaO.SiO₂ (C₂S): 10 to 35,    -   3CaO.Al₂O₃ (C₃A): 0 to 15,    -   CaO.SO₃ (C{haeck over (S)}): 0 to 10,    -   4CaO.3Al₂O₃.SO₃ (C₄A₃{haeck over (S)}): 2 to 15,    -   11CaO.7Al₂O₃.CaF₂ (C₁₁A₇.CaF₂): 0 to 5,    -   Total % CaF₂: 0.3 to 1.5 measured as CaF₂,    -   % Fe₂O₃: 0 to 0.5,        and a SO₃ content between 1.5 and 5% by weight. Clinker is        obtained through calcination of a raw meal containing CaO, SiO₂,        Al₂O₃ and CaF₂, using as fuel pet-coke with a sulfur content        higher than 5% at temperatures between 2192° F. to 2462° F.        (1200° C. and 1350° C.) without the addition to the raw meal of        any additive containing SO₃.

A cement clinker with percentages by weight of the following clinkerphases is preferred:

-   -   C₃S: 40 to 75,    -   C₂S: 10 to 35,    -   C{haeck over (S)}: 0 to 10,    -   C₄A₃{haeck over (S)}: 5 to 15,    -   C₁₁A₇.CaF₂: 2 to 5,    -   Total % CaF₂: 0.3 to 1.5 measured as CaF₂,    -   % Fe₂O₃: <0.5,

In another embodiment of the present invention, a cement clinker withpercentages by weight of the following clinker phases is more preferred:

-   -   C₃S: 40 to 75,    -   C₂S: 10 to 35,    -   C{haeck over (S)}: 0 to 10,    -   C₄A₃{haeck over (S)}: 5 to 15,    -   Total % CaF₂: 0.3 to 1.5 measured as CaF₂,    -   % Fe₂O₃: <0.5,

In yet another embodiment of the present invention, a cement clinkerwith percentages by weight of the following clinker phases is also morepreferred:

-   -   C₃S: 40 to 75,    -   C₂S: 10 to 35,    -   C₃A: 5 to 15,    -   C{haeck over (S)}: 0 to 10,    -   C₄A₃{haeck over (S)}: 2 to 10,    -   Total % CaF₂: 0.3 to 1.5 measured as CaF₂,    -   % Fe₂O₃: <0.5

Clinker calcination can be controlled to produce specific amounts of C₂Sand C₃A phases, such as the sum of the C₂S and C₃A clinker phases mustbe higher or equal to 10% by weight. Preferably C₃A clinker phase isabsent.

Clinker phase forming is facilitated by means of a CaF₂ percentage whichis about 0.3 to 1.5 measured as CaF₂ in the clinker. The preferred rangeis between 0.2 and 1.0% measured as CaF₂ in the raw meal.

A preferred SO₃ content in the clinker can be indicated as 1.5 to 5% byweight, mainly provided by means of the organic fuel such as pet-cokewith a sulfur % greater than 5%. However, it is also possible tooptionally complement the SO₃ content in the clinker with otherinorganic sources selected from the group consisting of plaster,anhydrite or industrial debris containing sulfur.

Corresponding calcium sulphate can be used to prepare finished whitePortland cement.

To optimize the setting reaction, according to an embodiment, it issuggested that the clinker be ground in a specific area of 465 to 775in²/g (3000 to 5000 cm²/g) measured according to the ASTM C-204 standardthrough Blaine.

Forming a sulfur-rich phase, calcium sulphoaluminate: 4CaO.3Al₂O₃.SO₃(C₄A₃{haeck over (S)}), shows an accelerated development of initialstrength compared to those of Portland cement, due to C₄A₃{haeck over(S)} hydration to form ettingite. Therefore, cements according to thepresent invention with C₄A₃{haeck over (S)} contents under 15% byweight, do not practically exhibit any expansion, for which, said cementhas an initial strength exceeding that of a common Portland cement.

On the other hand, during the clinker calcination of the presentinvention, less melted phase is formed (which is also due to the lowtemperature of calcination), which leads to a relatively porous clinker,consequently, the clinker has a better grinding capacity, and grindingcosts are reduced to the same specific area. Particularly, anotherrelevant advantage of the clinker herein, is that alite and belitecrystals sizes are less than 25 micrometers, which provides bettergrinding ease than the conventional white Portland cement clinker.

Clinker has a free lime percentage less than 1.5%, this is, it shows afree lime content similar to that of a white Portland cement clinker,but sinters at 392° F. (200° C.) under the traditional white Portlandclinker sintering temperature.

The present invention will be better explained in detail based uponseveral examples. However, following examples are provided only forillustrative purposes and are not intended to limit the scope of thepresent invention.

Sample 1 describes a cement free of C₃A, but comprises 9% by weight ofC₄A₃{haeck over (S)} and 4% by weight of C₁₁A₇.CaF₂.

Sample 2 describes a cement free of C₃A and C₁₁A₇.CaF₂, but comprises12% by weight of C₄A₃{haeck over (S)}.

Sample 3 describes a cement free of C₁₁A₇.CaF₂, but comprises 7% byweight of C₃A and 3% by weight of C₄A₃{haeck over (S)}.

Percentages of other clinker phases, SO₃ content in clinker, selectedcalcination temperature, as well as the total of SO₃ in cement, areshown in the table below, including compression strength values measuredafter 1, 3, 7, and 28 days.

To illustrate the advantages that can be obtained with cement of thepresent invention, a conventional Portland cement, calcined at 2642° F.(1450° C.), is also shown as sample 4. SO₃ in Calcination SO₃ Resistanceto compression Number Clinker phase (%) clinker Temperature Total(N/mm²) by number of days Sample C₃S C₂S C₃A C₄A₃{haeck over (S)} C₁₁A₇· CaF C{haeck over (S)} % ° F. (° C.) % 1 day 3 days 7 days 28 days 1 6124 0 9 4 2 3 2282 6 16 32 44 50 (1250) 2 61 24 0 12 0 3 3 2282 6 22 3451 65 (1250) 3 61 24 7 3 0 5 3 2462 4 15 29 43 57 (1350) 4 63 23 14 0 00 0.2 2642 3 20 27 39 52 (1450)

The data shows that sample 2, according to the present invention,exhibits a significant increase in compression strength at all of theindicated aging intervals. Samples 1 and 3, show comparable strengthsover time to those developed by sample 4 (which is the reference ofwhite Portland cement and calcined at 2642° F. (1450° C.). In addition,the white portland cement of the present invention has initial settingtime of from 10 to 45 minutes, measured according to the ASTM C-191standard through Vicat.

In a particularly preferred embodiment of the present invention, thewhite portland cement that comprises clinker of the present inventioncan be mixed with other materials such as limestone, slag, fly ashand/or other pozzolanic materials.

Even when certain embodiments of the present invention have beenillustrated and described, it should be noted that numerous possiblemodifications of such embodiments can be made and still be within thescope of the present invention in its broader aspects. The presentinvention, therefore, shall not be considered as limited excepting forwhat the prior art demands and for the spirit of the claims attachedhereto.

1. A white portland cement clinker, with the capacity to fix sulfurderived from an organic fuel having a high sulfur content, greater than5% S, used as a fuel in the calcination of said clinker, said clinkeradditionally exhibiting reduced fuel consumption during such calcinationand useful for producing a fast setting cement, and comprising amountsof clinker phases in percentage by weight, as follows: 3CaO.SiO₂ (C₃S):40 to 75, 2CaO.SiO₂ (C₂S): 10 to 35, 3CaO.Al₂O₃ (C₃A): 0 to 15, CaO.SO₃(C{haeck over (S)}): 0 to 10, 4CaO.3Al₂O₃.SO₃ (C₄A₃{haeck over (S)}): 2to 15, 11CaO.7Al₂O₃.CaF₂ (C₁₁A₇.CaF₂): 0 to 5, Total % CaF₂: 0.3 to 1.5measured as CaF₂, % Fe₂O₃: 0 to 0.5, and a SO₃ content between 1.5 and5% by weight obtained through the calcination of a raw meal comprisingCaO, SiO₂, Al₂O₃ and CaF₂, and using an organic fuel with a sulfurcontent higher than 5% as the main source of the clinker's SO₃ content,at temperatures between 2192° F. and 2462° F., without the addition ofany SO₃-containing additive to the raw meal as a main source of SO₃content in the clinker.
 2. The white portland cement clinker accordingto claim 1, wherein said clinker comprises the amounts of clinker phasesin percentage by weight, as follows: C₃S: 40 to 75, C₂S: 10 to 35,C{haeck over (S)}: 0 to 10, C₄A₃{haeck over (S)}: 5 to 15, C₁₁A₇.CaF₂: 2to 5, Total % CaF₂: 0.3 to 1.5 measured as CaF₂, % Fe₂O₃: <0.5, and aSO₃ content between 1.5 and 5% by weight obtained through thecalcination of a raw meal mainly containing CaO, SiO₂, Al₂O₃ and CaF₂,using as fuel pet-coke with a sulfur content higher than 5%, at atemperature about 2282° F., without any SO₃-containing additive to theraw meal as a main source of SO₃ content in the clinker, wherein theabsence of C₃A results in a clinker useful in the manufacture of cementsresistant to sulfates.
 3. The white portland cement clinker according toclaim 1, wherein said clinker comprises the amounts of clinker phases inpercentage by weight, as follows: C₃S: 40 to 75, C₂S: 10 to 35, C{haeckover (S)}: 0 to 10, C₄A₃{haeck over (S)}: 5 to 15, Total % CaF₂: 0.3 to1.5 measured as CaF₂, % Fe₂O₃: <0.5, and a SO₃ content between 1.5 and5% by weight obtained through the calcination of a raw meal mainlycontaining CaO, SiO₂, Al₂O₃ and CaF₂, using as fuel pet-coke with asulfur content higher than 5% as the main source of the clinker's SO₃content, at a temperature about 2282° F. without any SO₃-containingadditive to the raw meal, wherein the absence of C₃A results in aclinker useful in the manufacture of cements resistant to sulfates. 4.The white portland cement clinker according to claim 1, wherein saidclinker comprises the amounts of clinker phases in percentage by weight,as follows: C₃S: 40 to 75, C₂S: 10 to 35, C₃A: 5 to 15, C{haeck over(S)}: 0 to 10, C₄A₃{haeck over (S)}: 2 to 10, Total % CaF₂: 0.3 to 1.5measured as CaF₂, % Fe₂O₃: <0.5 and a SO₃ content between 1.5 and 5% byweight obtained through the calcination of a raw meal mainly containingCaO, SiO₂, Al₂O₃ and CaF₂, using as fuel pet-coke with a sulfur contenthigher than 5% as the main source of the clinker's SO₃ content, at atemperature about 2462° F., without any SO₃-containing additive to theraw meal
 5. The white portland cement clinker according to claim 16,wherein the addition of the amounts of C₂S and C₃A clinker phases ishigher than or equal to 10% by weight.
 6. The white portland cementclinker according to claim 16, wherein the total CaF₂ percentage amountin the raw meal is from 0.2 to 1.0% by weight measured as CaF₂.
 7. Thewhite portland cement clinker according to claim 1, wherein the SO₃content of the cement clinker is derived from pet-coke with a sulfurpercentage higher than 5%.
 8. The white portland cement clinker,according to claim 16, wherein the clinker SO₃ content is supplementedwith other, inorganic, sources selected from the group consisting ofplaster, anhydrite, and industrial debris containing sulfur.
 9. Thewhite portland cement clinker according to claim 16, wherein the alite,C₃S, and belite, C₂S, are crystals with sizes smaller than 25micrometers, which provides a better ease of grinding than theconventional white Portland cement clinker.
 10. The white portlandcement clinker according to any of claims 2 to 4 and 16, wherein saidclinker has a free lime percentage less than 1.5%.
 11. A white portlandcement comprising the cement clinker according to claim 16, wherein theSO₃ content of said cement is between 3.0 and 10%.
 12. The whiteportland cement according to claim 11, wherein the specific area is 465to 775 in²/g measured according to the ASTM C-204 standard throughBlaine.
 13. The white portland cement according to claim 11, wherein theinitial setting time is between 10 and 45 minutes measured according tothe ASTM C-191 standard through Vicat.
 14. The white portland cement,according to claim 11, wherein the resistance to compression measuredaccording to ASTM C-109 is about 15 to 25 N/mm² at 1 day, 25 to 35 N/mm²at 3 days, 40 to 55 N/mm² at 7 days, and 50 to 70 N/mm² at 28 days. 15.The white portland cement comprising the cement clinker according toclaim 1, mixed with at least one of other materials selected from thegroup consisting of lime, slag, fly ash and other pozzolanic materials.16. The white portland cement clinker according to claim 1, wherein theorganic fuel is pet-coke.
 17. The white portland cement according toclaim 11, wherein the SO₃ content of the cement is 3.5-10 wt. %.
 18. Amethod of producing a white Portland cement clinker according to claim16, comprising: subjecting a raw meal comprising CaO, SiO₂, Al₂O₃ andCaF₂, to a calcination at temperatures between 2192° F., and 2462° F.;using pet-coke having a high sulfur content greater than 5% S as thecalcination fuel and as the main source of the clinker's SO₃ content;said raw meal having been mixed so as to form upon calcination a whitePortland cement clinker having phases in percentage by weight, asfollows: 3CaO.SiO₂ (C₃S): 40 to 75, 2CaO.SiO₂ (C₂S): 10 to 35,3CaO.Al₂O₃ (C₃A): 0 to 15, CaO.SO₃ (C{haeck over (S)}): 0 to 10,4CaO.3Al₂O₃.SO₃ (C₄A₃{haeck over (S)}): 2 to 15, 11CaO.7Al₂O₃.CaF₂(C₁₁A₇.CaF₂): 0 to 5, Total % CaF₂: 0.3 to 1.5 measured as CaF₂, %Fe₂O₃: 0 to 0.5, and a SO₃ content between 1.5 and 5% by weight, withoutthe addition of any SO₃-containing additive to the raw meal as a mainsource of SO₃ content in the clinker.